Various information processing systems have been developed as a result of the rapid developments which have taken place in the information industry in recent years. Methods of recording and apparatus compatible with these information processing systems have been developed and adopted. In thermal transfer recording methods, the apparatus used is light and compact, there is little noise associated with the apparatus and they have excellent operability and maintenance characteristics. Moreover, since they also allow coloring to be achieved easily, these methods are the most widely used. Thermal transfer recording systems can be broadly classified into two types. In the first type (thermofusion type), heat is applied from the support side to a thermofusible ink which has been coated onto a support and the ink is melted in the form of a pattern corresponding to the pattern of heat applied and the ink is transferred to the recording medium (a thermal transfer image receiving material) to provide a hard copy. In the other type (thermomobile type systems), heat is applied from the support side in the same way as before to a thermal transfer dye donating material which has, on a support, a layer which contains a thermomobile dye, the dye migrates into the recording medium (thermal transfer image receiving material) in the form of the pattern in which the heat has been applied and a hard copy is obtained.
A thermomobile dye is, for example, a dye which can be transferred from a thermal transfer dye donating material to a thermal transfer image receiving material by sublimation or diffusion in a medium.
Synthetic papers in which polypropylene is the principal component are typical of the supports for thermal transfer image receiving materials used conventionally in thermal transfer recording materials. For example, thermal transfer image receiving materials in which a polyethylene resin layer is established as a dye receiving layer on a synthetic paper of which polypropylene forms the principal component have found practical application in thermomobile type thermal transfers. However, when synthetic papers of this type are used, they are thermally deformed by the heat from the thermal head. Specifically, curl, wrinkling and concavity type deformation occurs, and this reduces considerably the commercial value of the products.
The use of supports in which polyethylene is laminated on a paper in which natural pulp forms the principal component has been suggested as a means of overcoming these difficulties. However, when a general polyethylene laminated paper support has been used in the past the transfer densities have been low and it has not been possible to obtain a satisfactory maximum density. Problems have also arisen with image fading on storage at elevated temperatures after image formation.